The head stock spindle on my spinning lathe has a 1/2 x 13 thread. I can use a standard metal cutting tap to tap in wood, but I thought perhaps the cutter edges might be slightly differently shaped to cut wood cleanly. I have lots of small round sugar maple blanks to make chucks. Woodcraft lists a 1/2 wood tap, but doesn't say what thread count. They have not responded to my email yet.